Improvement in sectional steam-boilers



JOHN H MILLS Steam Generator.

VPATENT OEErE.

JOHN H. MHJLS, OE BOSTON, MASSACHUSETTS.

IMPROVEMENT` IN SECTIONAL STEAM-BOILERS.

Specification forming part of Letters Patent No. 121,395, dated November 28, 1871.

To all whom 'it may concern:

.Be it known that I, JOHN H. MILLS, of Boston, in the county of Suffolk and Commonwealth of Massachusetts, have made an invention of a certain new and useful System of Generating Steam; and do hereby declare the following to be afull, clear, and exact description thereof, due refer ence being had to the accompanying drawing, and in which- Figure l is a vertical and transverse section; Figs. 2, 3, and 4, vertical and longitudinal sections; and Fig. 5, a horizontal section of arange of generators constructed in accordance with my invention, Fig. 6 being aface elevation of one of the divisions to be explained.

My invention relates to cast-iron or sectional boilers or steam-generators, so called; and the object of my invention is to produce a generator of this kind which shall be, for all practical purposes, a safety one,which may be set up rapidly and economically, and in which the water is presented under the best conditions to be converted into steam. The generator in which my invention consists in one sense of the word is not sectional-that is to say, is not a boiler in which each section is dependent upon the other for operation, but each section, on the contrary, is in itself distinct and complete, comprising all the elements of a generator, including a grate-surface y and fire-space, having its own water supply and its own steam-escape, receiving its water and discharging its steam without regard to the others, the sections when aggregated or placed together simply servin g, by their shape and construction, to form a connected ire-box and iiues for the pas sage of the products of combustion. It is not necessary here to state in detail the various features of this invention, as they will fully appear in the following description of the apparatus I have shown in the drawing as embodying my invention.

The drawing accompanying and making part of this specification represents at A, especially in Figs. l and 2, one of the steam-generator sections, several of them being grouped together in regular order to obtain the requisite passage for smoke, Sac., and to produce a furnace. The structural character of the division A is throughout a tubular one, each tube being a continuation of some other, and a perfect communication being had throughout the series, the entire division, in its steam and water-pipes, grate-bars, furnace,

&c.,being produced from one homogeneous casting, and constituting in itself an independent and distinct steam-generating structure. Each upright side column of the generator A, as shown in Figs. l and 2, before named, is represented at a as erected upon and making part of the lower and horizontal pipe b, the said pipes a being surmounted by an arched or dome-shaped pipe, c. d represents a perpendicular pipe, 011e tO each side of the structure, whose lower ends unite with the outer extremity of the horizontal pipe b, this pipe d heilig' situated a short distance outside of and parallel to each column a, and being at top curved inward until it intercepts and unites with the latter at the foot of the dome or arched pipes c, d, and b, the said pipes c constituting the outer boundary of the generator, the said pipe d Serving to prevent loss of heat by radiation and to aid circulation, as hereinafter explained. c in the drawing represents a vertical central column, intercepting the dome c and rising a short distance above it, while in a downward direction the column extends until it intercepts a horizontal pipe, j', projected laterally between and entering the side columns a a at a point opposite the month of the outer side pipe d. g g in the drawing represent two curved pipes, each of which extends from about the center of one side column a, and unites with the horizontal pipe j' at the junction of the latter with the perpendicular column c, before named, while, lastly, h represents a short horizontal branch-pipe, which joins the side column a with the next adjacent outer pipe d, this branch h being situated opposite to and constituting a continuation of each curved pipe g. One extremity of the lower pipe b is pierced with an inlet-port, z', for supplying the boiler with water, while the opposite end is closed by a cock or plug. Owing to the vertical disposition of a greater part of the pipes of the generator any injurious amount of sediment contained in and precipitated from the water will nd its way ultimately to the lower pipe b, from whence it may be removed in one of two methodseither by expelling vit by the force of Steam in the generator, or, when the latter contains no steam, by removing it by mechanical means from the clearing-oriice K.

In order to produce a generator of considerable capacity and economy and to obtain smoke-pas sages, Svc., I combine together several of these divisions A, preferably eight or more, placed vertically together side by side. I preferably unite them at top by a long horizontal steam-pipe, B, by means of tubular screw-connection I, while at bottom I secure the divisions in a like manner to a horizontal water-supply reservoir, C, the only condition necessary to enjoin upon the person settingup the generator being that the divisions meet each other with a joint sufficiently close to prevent escape of caloric and smoke or gases between them. The union ofthe sections with their common steam-drum and common feed-pipe, the only joints through which they in any way may be considered to communicate with each other, is effected by means of lock-nuts, right-and-left screw-nipples, or other suitable means, admitting the ready disconnection of any one division from the drum and feed. rlhe connection of the feed with the sections is not made at a point vertically beneath their connection with the steamdrum, as this would interfere with the expansion of the sections, some of which may expand more than others; but it is made, as shown, off to one side of the boiler, whereby expansion can take place without any injurious effect. The group of divisions thus obtained is set or mounted in masonry or other proper covering in order to obtain a suitable ash -pit, D, beneath the furnace and a suitable chimney or smoke-fine, E, at rear. It will be seen by Fig. 3 ofthe drawing that the space or area H, inclosed within and surrounded by the pipes a, a, b, and g g, in aggregate will constitute the main combustion-chamber or furnace of the combined structure, and the space I, between the outer side pipes or legs d d and the said pipes a c, the auxiliary combustion-chamber; that the area F, inclosed by the pipes a c, f j', and g g, in aggregate constitute the first returnpassage or path for the product of combustion; and that the area G, inclosed by the pipe f and dome o, forms the escape-passage into the iiue E ofthe chimney.

In order to obtain a proper connection at rear between the furnace I-I and passage E I omit or remove from the last division A but one, the oblique curved pipes g, and the pipes h and a; while in order to obtain communication between the passage F and G I omit from the front division the horizontal pipes ff. The last division but two of the series A A, Ste., is a solid between its pipes, with the exception of the smokeexit portion G, the purpose of such a construction being to form a bridge-wall to the furnace and to force the gases, etc., to pass into and through the side or auxiliary combustion-chambers I, which this barrier compels them to do before they can find their way to the passage F. The lower end| of each pipe or column al is cast upon each front and rear side with a three-sided wall or inclosure, open at bottom, and so disposed as to constitute, when two divisions are united, cells or reservoirs a for reception of oxygen, which passes upward into them from the ash-pit below, small in sterstices of air-ports p p, Sto., being pierced through the walls, by which air ilows or is drawn from them and into and mixed with the gases in the furnace and the auxiliary combustion-chambers I I. In order to obtain a grate-surface for the furnace I erect upon the crown of each horizontal pipe b a series of spurs or bars, q g, Ste., the bars being disposed at equal distances asunder and at right angles to the longest plane of the pipe, and being of a length about equal to the extreme thickness of the entire division A, the discrepancy between the two measurements being in manner and for purposes hereinafter stated. As the bars q of each division are disposed in longitudinal alignment with each other a general grate-surface is thus obtained, the air for supplying the furnace passing between the base from the ashpit below. In order to deliver as great a quantity of oxygen a-s possible to the fuel I make in the bars one or more cross-passages, r r, 85e., as shown in Fig. 5 of the drawing, these passages being in aggregate disposed obliquely with respect to each other and the greatest plane of the generator, in order that a poker or hoe drawn over the grate shall not drop into them. The upper faces of the bars q should be so far elevated above the main body of the pipe b as to remove the fuel from the injurious effect of the cold water, at the same time availing of this cool condition of the pipe to such an extent as to protect the bars from being greatly damaged from the fire upon them. L represents a tilting-plate or trap, so applied to the bottom of the last generator but one of the series that it may be tilted or inclined and by this means dump in the ashpit below any collection of refuse matter which would otherwise accumulate at this point. The line at which the water in each generator should be maintained is shown at g h, in the various figures in the drawing. Unconsumed products of combustion from the fuel in the furnace H pass rearward from such furnace or main combustion-chamber and the auxiliary side chamber I, (which, in reality, are a piart of the furnace,) in their course absorbing oxygen, which issues from the cells n before named and meets the gases at about a right angle. The gases, 86e., by the time the latter end ofthe passage Fis reached, become perfectly aerated, and before the exit of the final passage Gr is reached are consumed, having imparted to the water in the various pipes of the generator the caloric held by them.

An importa-nt advantage incident to my system of generators is the facility with which any one division may be isolated or removed from the group, since to accomplish this it is only necessary to sever its connection with the supply tank or conduit and the steam-receiving pipe B.

Referring to Figure l of the drawing, it will be seen that the various pipes a, b, d, g, h, and a portion of f are full of water. The heat of the furnace H, culminating at its crown, generates by direct action steam within the pipes y and a, which constitute in aggregate the circumscribing walls or boundary of the furnace, while the water contained in the pipes d, which constitute the outer boundary of the generator and are subjected to a comparatively low temperature, is of such a temperature, owing both to the exposed condition of said pipes cl and to the constant influx of a fresh supply of water from the feedwater reservoir, as to induce throughout the entire group of pipes Which makes up each division A an automatic circulation, which practice has demonstrated to be very effective and valuable in its results. A furnace constructed as herein described may, by omitting the steam-dome por- In this modication'the spurs or bars g q before mentioned are formed upon a long inverted V- shaped bar of iron of a length equal to the Width of the furnace, and which, when in use, straddles the lower horizontal pipe b of the generator. Under this arrangement it will be seen that should one portion of the general grate-surface of the furnace become injured or ruined it may be instantly removed and replaced by a new one with little trouble.

To this arrangement, however, I here lay no claim per se, as I contemplate making it the subject of a separate application for Letters Patent.

What I claim, and desire to secure by Letters Patent, is'as follows:

l. A cast-iron steamgenerator composed of one homogeneous casting, consisting of the pipes a b c d e f g, arranged as described, and the elevated grate-surface q erected on the lower waterpipe b, substantially as shown and set forth.

2. A steam-generator composed of sections formed each of a single casting, With are-space, a grate-bar erected on and elevated above the lower Water-pipe, and flanges to form air-pockets, so that when said sections are placed side by side together the furnace or fire-box, elevated gratesurface, and air-pockets Will be formed Without further fitting, substantially as herein shown and described.

3. The air-pockets 'n With orifices p formed in the side Walls and between the sections of the generator, substantially as and for the purpose set forth.

4. A steam-generator provided with passages arranged, as described, so that the products of combustion shall first divide and pass laterally from the furnace into and through combustionchainbers formed on each side thereof, thence upward in rear of the bridge-Wall and over the furnace, effecting one or more traverses of the entire length of the generator before escaping into the chimney, substantially as set forth.

Witnesses: JOHN H. MILLS.

FRED. CURTIS,

EDWARD GRIFFITH. (148) 

